Necessity of vancomycin trough concentrations to manage uncomplicated acute bacterial skin and skin structure infections: a laboratory stewardship analysis.

Background: Recent recommendations by the American Society of Health System Pharmacists and Infectious Disease Society of America have provided guidance regarding vancomycin dosing and monitoring in serious infections (including methicillin-resistant Staphylococcus aureus); however, trough monitoring for uncomplicated acute bacterial skin and skin structure infections (ABSSSI) were not addressed. Vancomycin use appears to lead to a low incidence of acute kidney injury with short durations and a low trough goal (10-15 mg/L). Nevertheless, clinical studies have found no difference in clinical outcomes for ABSSSI regardless of vancomycin level. Therefore, it can be posed whether trough monitoring is necessary in this patient population.

Methods: This is a retrospective cohort study comparing vancomycin therapy duration for ABSSSI in adult, general medicine patients who received scheduled vancomycin with an initial creatinine clearance rate of ≥50 mL/minute and had at least one vancomycin trough. The objective of this study was to determine if vancomycin treatment duration differs for patients with ABSSSI with a sub-therapeutic vancomycin trough (ST; <10 mg/L) compared with therapeutic trough (TT; ≥10 mg/L).

Results: There were 39 (67.2%) patients with ST compared with 19 (32.8%) with TT. A similar median vancomycin treatment duration for ST (48.25 hours) and TT (59.5 hours; p=0.65) was found. There was no statistical difference for hospital duration, time from last trough to vancomycin discontinuation, or incidence of acute kidney injury (p>0.05 for all).

Conclusion: Patients with ST and TT had similar vancomycin durations and clinical outcomes. It may be prudent for institutions to address vancomycin trough laboratory stewardship and associated costs.